h1{
    text-align: center;
    /*小写转大写*/
    text-transform: uppercase;

}
h2{text-align: center; !important;}
h3{text-align: center;}
h4{text-align: center;}
h5{text-align: center;}
h6{text-align: center;}
p{
    /*首字母大写*/
    text-transform: capitalize;
    /*缩进*/
    text-indent: 2em;
    font-family: serif;
    font-size: 30px;
    font-weight: bold;
    color:#523;
}

div{
    width:100%;
    height: 20%;
    background-color: #c3e1ea;
    background-image: url("#");
    margin: 40px;/*外边距*/
    border: 40px;/*边框*/
    padding: 40px;/*内边距*/
}
.demo{
    background-image: url("../img/2102.jpg");
    background-repeat: no-repeat;
    background-attachment: fixed;
}